A nonvolatile switching element has been developed recently, which can be re-written with a small area (hereinafter, referred to as a rewritable nonvolatile switching element).
As shown in FIG. 15A, a rewritable nonvolatile switching element 1 includes an anode 10 of a first electrode, a cathode 12 of a second electrode, and an ion conductor 11 sandwiched between the two electrodes.
The anode 10 is an electrode which supplies a metal ion to the ion conductor 11 and is mainly composed of copper. The cathode 12 is an electrode which does not supply a metal ion to the ion conductor 11 and platinum or the like is utilized. The ion conductor 11 has such a nature as to move the metal ion supplied from the anode 10 and tantalum oxide or the like is utilized.
FIG. 15B shows the state that the rewritable nonvolatile switching element 1 is ON, that is, the conduction state between these two electrodes. These two electrodes become the conduction state by applying a voltage Von to the anode 10 to and connecting the cathode 12 to the ground.
FIG. 15C shows the state that the rewritable nonvolatile switching element 1 is OFF, that is, the cut-off state between these two electrodes. These two electrodes become the cut-off state by connecting the anode 10 to the ground and applying a voltage Voff to the cathode 12.
Turning the rewritable nonvolatile switching element 1 ON or OFF is called programming. The ON state and the OFF state of the rewritable nonvolatile switching element 1 are held even if the power supply is cut.
A programmable cell 5 is disclosed in the Patent Literature 1, which uses the rewritable nonvolatile switching element 1 as shown in FIG. 16. A horizontal programmable wiring group 100 intersects a vertical programmable wiring group 200, an input wiring group 310 of a function block 2, and an output wiring 400 of a function block 2 at an intersecting area 5000 of these wiring groups. An intersecting point of each wiring is coupled with each other by a rewritable nonvolatile switching element 1A. The adjacent horizontal programmable wiring groups 100 are coupled with each other by a rewritable nonvolatile switching element 1B and the adjacent vertical programmable wiring groups 200 are coupled with each other by a rewritable nonvolatile switching element 1B.
The rewritable nonvolatile switching element 1A is an element in which a horizontal wiring and a vertical wiring are connected to terminals 14 and 13 of the rewritable nonvolatile switching element 1 as shown in FIG. 17A. The rewritable nonvolatile switching element 1B is an element in which adjacent wirings are connected to the terminals 14 and 13 of the rewritable nonvolatile switching element 1 as shown in FIG. 17B.